TB-3PO — Generative Acid Bassline Sequencer for Schwung

A JS-only module for Schwung that ports the Phazerville Hemisphere Suite TB_3PO applet to Move hardware. Generates 303-style patterns with density / accent / slide probabilities, scale-locked notes, pattern banks, mutate, and multiple playback directions.

Two independent slots (A and B) run in parallel, each with its own pattern, MIDI channel, and bank set. Pair each slot in a shadow slot with a resonant monosynth (schwung-303, Bristol, OB-Xd, Raffo Moog, …) — TB-3PO emits MIDI only; the squelch comes from your synth.

Install

From the Schwung Module Store, or manually:

git clone https://github.com/charlesvestal/schwung-tb3po
cd schwung-tb3po
./scripts/build.sh && ./scripts/install.sh

Requires Schwung v0.9.8 or later (needs the suspend_keeps_js capability).

Usage

1. Open Tools (Shift+Vol+Step13) → pick TB-3PO.
2. Set the MIDI channel for slot A on the CHANNEL page (Step button 4). Switch to slot B with T3 and set its channel.
3. Load synths into shadow slots and set their receive_channel to match. For the easiest path, pair with schwung-303 on each channel.
4. Back → close an open list, or suspend (both slots keep sequencing while you play Move).
5. Shift+Back → full exit.
6. Re-open from Tools menu → resumes with patterns + position intact.

Slots & Modes

Track buttons select which slot is active and what the 8 front-panel knobs do:

Button	Slot	Mode	Knobs control
T1	A	3PO	sequencer params (density / accent / slide / oct / root / scale / length / gate)
T2	A	303	live CCs to a schwung-303 on slot A's channel
T3	B	3PO	sequencer params for slot B
T4	B	303	live CCs to a schwung-303 on slot B's channel

Both slots sequence at all times — the buttons just switch which slot the knobs and pads edit. Active slot/mode lights bright (teal = 3PO, orange = 303). 303-mode buttons are dark unless a 303 plugin is reachable in some shadow slot.

Pages (Step buttons 1–5)

1. PERFORM — header, step grid, pattern info
2. MUTATION — jog-edit Density / Accent / Slide / Octaves (or 303 Control 1 in 303 mode: live K1–K4 readouts)
3. SCALE — jog-edit Root / Scale / Length / Gate (or 303 Control 2 in 303 mode: live K5–K8 readouts)
4. CHANNEL — jog-edit MIDI out channel (1–16) for the active slot
5. HELP — on-screen pad map

Option lists

Hold a knob whose cell is an enum (MIDI Ch, Direction, Root, Scale, Length) and click the jog: its options open full-screen. The jog or the knob still under your hand scrolls, a click sets, Back cancels. Simply turning such a knob raises the same list for about 0.7 s — a read-out of where you have landed, not a question, so there is nothing to cancel and Back just takes it down.

Knobs — 303 mode (CC controller)

When in 303 mode, the 8 knobs send standard 303-style CCs to the loaded 303 plugin on the active slot's channel:

Knob	Param	CC
1	Cutoff	74
2	Resonance	71
3	Decay	75
4	Env Mod	70
5	Accent	16
6	Volume	7
7	Drive	12
8	Drive Mix	13

On entering 303 mode, knob state syncs from the plugin's current values so the first turn doesn't jump.

Pads (4 rows, top = row 3)

• Row 3 — steps 1–8 of the current step page
• Row 2 — steps 9–16 of the current step page Tap cycles rest → note → accent → slide.
• Row 1 — pattern banks 1–8. Tap = recall (queued to next bar if playing). Shift+tap = save current to bank.
• Row 0 — actions:

Pad	Action
1	NEW — regenerate pattern from a fresh seed
2	MUT — nudge ~25% of existing steps
3	DIR — cycle Fwd / Rev / Ping / Rnd
4	Ch− — decrement MIDI out channel
5	Ch+ — increment MIDI out channel

Hardware buttons

• + / − — transpose ±1 octave (clamped ±48 semitones)
• ← / → — step page (for 24- and 32-step patterns)
• X (Delete) — CLEAR; gated, requires Shift+X
• Undo — revert last NEW / MUTATE / CLEAR
• Play — transport (passthrough to Move firmware)

LED colors

• Steps — white = note, red = accent, blue = slide, off = rest. Cursor blinks yellow.
• Banks — purple = current, teal = filled, off = empty. Yellow flash = bank queued for next-bar recall. With Shift held, the whole row pulses red/pink (save targets).
• Action row — teal NEW, indigo MUT, orange DIR.
• Pages — green = current page, white = available.
• Track buttons — bright teal = active 3PO, bright orange = active 303; dark grey = inactive; off = no 303 reachable.
• Knob rings — lit for the encoders that do something on the page you are on (knobs 1-4 white, 5-8 amber), brightness following the value; dark means turning it does nothing.

Sync

Tempo follows Move's project BPM automatically. TB-3PO runs free (not gated by Move's transport) — use Move's Play button to start/stop.

Suspend / exit

• Back — closes an open option list (or the list raised by turning an enum) first; with nothing open, hides TB-3PO while both slots keep sequencing in the background.
• Shift+Back — full exit (release notes, unload).
• Shift+Vol+Back — also suspends.
• Shift+Vol+Jog Click — also full exit.
• Re-open from Tools menu → resumes with patterns + position intact.

License

GPL-3.0 — inherited from the Phazerville Hemisphere Suite upstream (TB_3PO.h). Schwung itself is MIT; this module is a separate repository and keeps its own license.

Credits

• Algorithm: djphazer and Hemisphere Suite contributors — O_C-Phazerville.
• Port: Charles Vestal.